[5] In 2068, Black is seconded to command the Zero-X spacecraft for a crewed mission to Mars, assigned with investigating anomalous radio signals detected by the Spectrum Organisation.
Previously, Earth was aware only of the existence of rock snakes on the planet (as seen in Thunderbirds Are Go); consequently, Black is alarmed to discover a fully-developed alien city on the Martian plains.
After using their power of "reversing matter" to reconstruct their city, the Mysterons condemn humanity's unwarranted aggression and declare a retributive "war of nerves" against Earth – the first act of which will be the assassination of the World President.
As the aliens go on to state that "one of you will be under our control", Black undergoes a dramatic change of appearance as he sits in the cockpit of the MEV, his expression hardening and his face becoming pale – thus, he is transformed into the primary instrument of the Mysterons' campaign of vengeance.
Capturing Symphony Angel while evading their ground forces, he deliberately subjects her to radiation inside an atomic centre, but does not kill her and allows her to escape.
According to text features in the comic TV Century 21 and related publications, Black was born Conrad Turner in Manchester, England (though until his corruption at the start of "The Mysterons", he speaks with a North American accent) and was orphaned at seven months as a result of a brief nuclear war.
[13] In the episode "Treble Cross", an air force test pilot unexpectedly survives an assassination attempt by the Mysterons and aids Spectrum in another effort to apprehend Black.
If under threat of imminent capture, Black is able to teleport away from danger – an action demonstrated in the episodes "The Heart of New York", "Model Spy" and "Inferno".
However, he is shown wearing his uniform in various comic stories where there is no immediate demand for secrecy or when his mission would benefit from it, such as when the Mysterons took control of a robot production facility or when Black tried to manipulate an amnesic Scarlet into helping in an attack on a major conference being held to justify Spectrum's funding.
By contrast, after his Mysteronisation he is an almost stereotypical villain, taking pleasure in the acts of murder that he commits; in one episode, he leaves Captain Scarlet chained up next to a doomsday device, complete with digital countdown.
According to promotional materials, Conrad Lefkon was born in Brooklyn, New York and was the son of a local crime lord, and joined the army to escape from the "family business".
"[15] Eamonn McCusker of website The Digital Fix states that Black's vengefulness "knew no limits", noting that in one episode ("The Heart of New York") the character kills a gang of human bank robbers posing as Mysteron reconstructions because their "impersonation [...] had aroused his ire.
"[18] Daniel O'Brien, author of SF:UK: How British Science Fiction Changed the World, states that Black's characterisation as a villain is "to no one's great surprise".
[22][23] On black-and-white dualism, Guyanese actor Cy Grant, who voiced Lieutenant Green and praised the series for its multiculturalism, commented that "the 'darkness' of the Mysterons is most easily seen as the psychological rift — the struggle of 'good' and 'evil' — of the Western world as personified by Colonel White and his team.